“Come up to the roof,” Mab proposed when she got back to Aspley Guise. “We won’t get another warm day like this until spring, and you look peaky.”

“It’s the new block.” Still the new block, even though the naval section had moved over in August. “I never thought I’d miss that creaky old hut, but these big blocks have all the boundless charm of a TB sanitarium. Conveyor belts cranking away, pneumatic tubes, Park messengers whizzing in and out . . .” Osla shook off her blue funk, shimmied into her bathing suit (midriff-baring white dotted with red cherries), and followed Mab up the attic stairs to the rooftop, which was flat, remote, and perfect for sunbathing. Osla laid out her towel as Mab stripped down to her unmentionables; no one was going to see them up here. The day was summer-warm, more like June than October—Osla watched a Hurricane drone overhead from the nearest training base and began working through a comic weather report for Bletchley Bletherings: Warm and hazy, with a thirty percent chance of Messerschmitts! Writing BB was about the only thing that gave Osla’s days any fizz now.

“I got your Vigenère message.” Beth’s voice floated behind them. Even without the Dread Mrs. Finch snooping, the three of them had never dropped the habit of leaving notes for each other in code. Up on the roof, bring your bathing suit! Osla had ciphered before dashing upstairs after Mab.

“Letter came for each of you,” Beth continued, wind stirring her blond hair as she came up onto the roof. Osla had marveled before at the change in her quietest billet-mate—something had shifted in Beth, beyond the hair and lipstick. She hardly seemed to be present now unless she was on her way to BP, straining like an eager greyhound to get to work. If she wasn’t working, Beth didn’t even seem to be there. Not in the please don’t look at me way of the silent, henpecked girl Osla had first met—more in the sense that she wasn’t really interested in anything that took place outside Knox’s section. That, or heading to Cambridge every day off to listen to records; something else the old Beth would never have done, so Osla supposed it was progress . . . Still, there was something Osla found unsettling in her billet-mate’s preoccupied stare lately.

“For you, and you—posted here, not through the London PO Box.” Beth handed over the letters, sitting down on the slates and tilting her face upward. “That plane’s doing another loop.”

“A Hurricane. I used to make them.”

“Did you?” Beth asked vaguely.

“Yes.” Osla heard her voice grow tart. “And you’ve heard that story several times. Can’t you at least pretend not to utterly ignore anything that isn’t in bally code?”

Beth looked puzzled. Osla sighed and tore open her letter, getting a familiar jolt of joy as she recognized Philip’s writing.

Darling Os—I haven’t had a letter in ages. Did I do something to offend? Don’t tell me you’ve met someone else, because if you have, I’ll paste him.

On the heels of joy: pain. Because she couldn’t tell Philip why she’d stopped writing.

You might hurt for a while, Osla told Philip silently, but I’m keeping you safe. Her commander had been clear—if she failed to keep Philip at arm’s length and there was another security breach, Osla wouldn’t be the only one called to account. Philip could be too, and he had more to lose. His shining new lieutenancy, his pride in serving at sea, his acceptance from the royal family when he hardly had family of his own left . . . all that could go if there was talk of treason.

He would never recover from a blow like that. Even a brave man like Philip had his Achilles’ heel.

I’m protecting yours, Osla thought, folding up the letter. Even if you never know it.

Her ears rang suddenly as Mab let out a whoop. “He’s coming home! Francis is coming home!”

“From Inverness?” Osla asked as Beth said, “From where?”

“I thought they were going to keep him there till he sprouted heather.” Mab shuffled a ream of pages, still reading—her husband was always writing her thick packets, and all summer long she’d been scribbling thick packets back.

Osla took her involuntary tendril of envy, squashed it flat, and stamped on it repeatedly. “How long has it been now?”

“Four months, ages longer than he originally thought . . .” Mab hugged her knees. “He’ll have three days, the eighth through the tenth of November. How am I going to wait another month? He wants me to take the train to Coventry, and bring Lucy.” A dizzy smile. “He’s going to show us his house—the house we’ll all live in after the war.”

Osla’s envy raised its head again, and she gave it another vicious stamp. “Absolutely topping!”

“Come with me,” Mab said promptly. “I’ll need someone to help look after Lucy.”

“So you can boff your husband senseless each night?” Beth said.

Osla and Mab turned to stare at her. “Where did you learn an expression like that, Miss Finch?” Mab laughed. “Clearly you have been falling into bad company.”

“Beth, are you sloping off to meet some fellow?” Osla exclaimed in mock horror. “All these Cambridge Sundays . . .”

She meant it as a joke but Beth looked upward, avoiding eye contact. “That Hurricane’s back.”

Osla’s senses pricked. Maybe if Beth seemed distant lately there was a better explanation than overwork. “Don’t get in a flap, tell me—”

“Look, Coventry—can one of you come?” Mab pleaded.

The pink in her cheeks made Osla forget about Beth. Mab was positively shining, not with the cool, hard confidence she’d radiated from the day they met, but with pure joy. She’s in love, Osla thought. She may have married Francis for hardheaded reasons, but now she’s head over heels.

“Well, I’d better come along so you get your idyll,” Osla said lightly. Three days alongside a husband and wife fizzing with mutual adoration—this was going to require a lot of mental stamping. But Osla couldn’t say no, not when Mab sat there visibly clutching her own happiness like it was the most fragile of vases. “If you brought Beth, she’d get the swithers, disappear down the center of a rose for an hour, and next thing you knew Lucy would turn up in Timbuktu.”

The Hurricane circled round again, even lower. Mab grinned, eyes sparkling. “Let’s give him something to look at, ladies.”

She stripped off her brassiere and whirled it over her head as the plane droned overhead. Osla pulled off the top of her bathing suit and did the same, laughing. “No, thank you,” said Beth, keeping her blouse buttoned, but she waved. The Hurricane waggled its wings in return, and Mab blew a kiss. “Guess what, flyboy!” she shouted upward. “My husband’s coming home!”

Chapter 43

* * *

FROM BLETCHLEY BLETHERINGS, NOVEMBER 1942

* * *

What on earth is the local RAF squadron to do now that it’s too cold for the BP ladies of Woburn Abbey and Aspley Guise to go rooftop sunbathing in their skivvies? Go buzz the Fr?uleins in Berlin, boys, and drop a few bombs while you’re at it . . .

* * *

One hour’s break for every eight-hour shift. Sometimes Beth and Harry were too exhausted to do anything but bolt sandwiches side by side in the canteen before heading back to their respective blocks, but more often than not they’d trade a wordless glance, make separately for the Park’s abandoned air-raid shelter, and fall on each other. It wasn’t lovemaking in there, when they were inside BP’s clock; it was fast, urgent relief. In Cambridge on days off, they could stretch out on the cot in Scopelli’s, talk, laugh—but coming together in the middle of a shift, they were both too far inside Enigma’s pathways to pull entirely free.

Beth’s mind had been knotted up for weeks in the Spy Enigma; by the time she fell into Harry’s arms on break, all she wanted was a few minutes to stop thinking. Harry was nine months into the U-boat traffic lockout; after four hours of fruitless work he’d slam into the air-raid cellar with every muscle drawn stone-hard, balanced on such a knife edge of frustration and rage that all he wanted was an outlet—an urge Beth understood perfectly. They’d take a few silent minutes to claw it all out on each other’s flesh and then trade soft, wordless kisses and go back to the code.